A DFT study of arsine adsorption on palladium doped graphene: Effects of palladium cluster size

Graphical abstract: The relationship between charge difference and adsorption strength demonstrates that charge migration from Pd_n-SDG to AsH_x significantly enhanced adsorption strength, the Pd₆ clusters doped SDG with a steep slope is recommended as a superior adsorbent material for AsH₃ removal from gas stream. - Highlights: • Pd atom and Pd clusters bind strongly onto the defective graphene surface. • Larger size of Pd cluster adsorbs arsine and its hydrogenated products stronger. • Order of adsorption strength on Pd_n doped graphene: As > AsH > AsH₂ > > AsH₃. • Charge migration characterizes the strong adsorption of AsH₂, AsH, and As. • Pd cluster doped graphene is thermodynamically preferable for arsine removal. - Abstract: In this study, we have investigated the size effects of palladium (Pd) doped single-vacancy defective graphene (SDG) surface to the adsorption of AsH₃ and its dehydrogenated products on Pd using density functional theory calculations. Here, Pd cluster binding study revealed that Pd₆ nanocluster bound strongest to the SDG surface, while adsorption of AsH_x (x = 0–3) on the most stable Pd_n doped SDG showed that dehydrogenated arsine compounds adsorbed onto the surface stronger than the pristine AsH₃ molecule. Charge analysis revealed that considerable amount of charge migration from Pd to dehydrogenated arsine molecules after adsorption may constitute strong adsorption for dehydrogenated arsine. In addition, study of thermodynamic pathways of AsH₃ dehydrogenation on Pd_n doped SDG adsorbents indicated that Pd cluster doping on SDG adsorbent tends to be thermodynamically favorable for AsH₃ decomposition than the single-Pd atom doped SDG. Hence, our study has indicated that Pd₆ clusters doped SDG is more advantageous as adsorbent material for AsH₃ removal.